A major goal of this project is to determine the nature of the associations established when infrahuman organisms (rats, pigeons, and goldfish) are exposed to various explicit or implicit dependencies between discrete external stimuli, drive states, general situational (contextual) cues, and responses. Special post-conditioning assays (.e.g., summation, retardation, generalization, substitution, and expectation techniques) will frequently be used in attempts to "unmask" or detect evidence of associative learning that is not manifested in performance measures obtained during the presumed learning experience; experiments along these lines include studies of backward associations, sensory preconditioning, learning by observation, context conditioning, and conditioned inhibition. In this and most of the additional proposed work, the phenomena of sign-tracking (which includes auto-shaping and the feature-positive effect)--as measured by the development of responses directed toward or away from predictive stimuli--will serve as tools for investigating factors affecting learning and performance (e.g., the stereotypy of discrete and contextual cues, partial reinforcement, positive vs. negative relations between stimuli and reinforcers, and the type and amount of information provided by a CS), but other Palovian and operant tasks will also be employed. The role of certain types of perceptual interaction among simultaneously- or successively-presented stimulus elements (e.g., proximity, similarity, relative salience, spatial organization) will be assessed in various situations, frequently along the lines suggested by the classic Gestalt laws of perceptual organization. In addition, we will continue specific research on spontaneous recovery, disinhibition, extinction, and stimulus generalization. The proposed work seems to have definite theoretical implications for the validity of the operant respondent distinction, the applicability of response-centered vs. perception-centered approaches to learning, the importance of reinforcement in learning and performance, and the utility of "surprise" and "informativeness" as explanatory concepts. We expect the nature of the associations formed in various "simple" Pavlovian and operant tasks to be considerably more complex than usually thought to be the case for infrahuman subjects.